A host computer typically writes to and reads from registers and memory locations of a storage device using a bi-directional serial data input/output line (SDIO). For example, the host may send a 16 bit word including a 1 bit mode (specifying read or write), followed by a 7 bit address, followed by 8 bits of data. During write mode, the 7 bit address may specify a write address, and the 8 bits of data may specify the data to be written. During read mode, the 7 bit address may specify a read address, and the 8 bits of data may be the 8 bits of data being read from the specified address. Other variations are also possible.
Typically, the host will need to send many consecutive words to the storage device, thereby requiring that the storage device quickly deal with each word as it is received. However, the storage device may not always be able to deal with each word quickly because, for example, other components within the storage device may have higher priority access to the busses, registers and/or memory within the storage device that need to be accessed to deal with the read or write requests sent from the host. This may slow down the serial transfer rate between the host and the storage device. This may also require that the various components within the storage device operate at a much higher speed than the serial transfer rate.
There is a desire to overcome the above mentioned constraints. More specifically, it is desirable to increase (rather than limit) the serial transfer rate between the host and the storage device. Additionally, it is desirable to relax (rather than increase) operating requirements of a laser driver, while still being able to achieve a faster serial transfer rate between the host and the storage device containing the laser driver.